// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_AUTO_RESET_H_
#define BASE_AUTO_RESET_H_

#include "base/macros.h"

// base::AutoReset<> is useful for setting a variable to a new value only within
// a particular scope. An base::AutoReset<> object resets a variable to its
// original value upon destruction, making it an alternative to writing
// "var = false;" or "var = old_val;" at all of a block's exit points.
//
// This should be obvious, but note that an base::AutoReset<> instance should
// have a shorter lifetime than its scoped_variable, to prevent invalid memory
// writes when the base::AutoReset<> object is destroyed.

namespace base {

template <typename T>
class AutoReset {
public:
    AutoReset(T* scoped_variable, T new_value)
        : scoped_variable_(scoped_variable)
        , original_value_(*scoped_variable)
    {
        *scoped_variable_ = new_value;
    }

    ~AutoReset() { *scoped_variable_ = original_value_; }

private:
    T* scoped_variable_;
    T original_value_;

    DISALLOW_COPY_AND_ASSIGN(AutoReset);
};

} // namespace base

#endif // BASE_AUTO_RESET_H_
